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UNITED STATES Planear. OFFICE.

FRANCIS o. Low'rnonr, 0F cnAMBEnsBcne, NEW JERSEY.

Bpecilication 'formingpart of Letters Patent No. l 69, da ed January 26, 1875; application filed December 21, 18'] To all'whom it Itay concern: 4

Be itknown that I, FRANCIS C. Low'rnonr,

-of Chambersburg, Mercer county, New Jer- -tion of a modified bar for-the 'same purpose; Fig. '3, a section ot' the post; Fig. 4, a front view of the same, showing the diagonal conn'ections; Fig. 5, a lsection of across-strut oi' a truss-iiame bridge; and Fig. 6 a modifical tion.

The anglebar A, Fig. 1, has a web, a, which may be varied in thickness, according to the duty which it has to perform as apar-tot' a compression member ot' any structure, and at one edge of the web is a iiangc, l), ot appropriate thickness, and always of sntiicient depth to receive suitable bolts or rivets, the opposite edge being thickened at d. It will be seen that thc'web of this bar can be readily varied in thickness by the adjustment of the rolls, the ange d increasing in depth'between the points :c :n as the web a is increased in thickness'. VVhat-ever may be the thickness of the web, the ange l should always pre-v sent a bulky mass of metal compared with the web, and this will always be the case whether the web is thick or thin. When the Yweb is thin, for instance, as shown in Fig. 3, the flange d is much thicker than the web, and when the latter is'increased in thickness, as represented by dotted lines in Fig. 1, the flange d, although not increased in depth, has such increased thickness imparted to it as to insure the. desired massiveness. The .two iiangesb and d maybe on the same side of tbe.web,-as shown in Fig. 2, instead of being on opposite sidesffor, if desired, there may bea iiange, d, on both sides of the web, but in most cases I prefer a bar of the sectional form shown in Fig. 1. Figs. 3 an`d 4 represent the section and front view of a post or the section andplan of an upper chord of a bridge. It is composed of four of the above-dbscribed angle-bars, combined with diagonal connecting-bars, in a manner so clearly shown in the drawing as to need no detailed description.

It will be evident to those 'familiar with truss-frame bridges that, in constructing a^ post, the connecting-bars u maybe readily arranged for the passage ot' the main .and counter diagonale.

In Fig. ,3 it will be observed that the connecting-plates u are placed `between the adjoining flanges b of each' pair of bars, but in the modification, Fig. 6, the adjoining angcs b are situated between the bars, either plan being adopted, as circumstances may suggest. A contimions plate or plates may be substituted for the connecting-bars.

When the angle-bars" have to be combined to form the upper vertical cross-strut oi a truss-frame bridge, I prefer to arrange them. in the manner shown in Fig. 5, so that no lo( gment may bc presented for warteror snow.

A post or compression member composed of the within-described angle-bars, combined with connecting bars or plates u, as specified.

In testimony whereof I have signed my naine to this specitication in the presence ot two subscribing witnesses.

F. C. LOWTHORI".

Witnesses:

J No. A. BELL,

MARRY SMITH. 

